Pennsylvania may finally be earning its battleground reputation

Police ride bicycles down Market Street toward City Hall ahead of the Democratic National Convention in Philadelphia, July 24, 2016.

Democrats are gathering for their convention this week in Philadelphia, a bastion of support for the party in a state that has not voted for a Republican presidential candidate since 1988.

With 20 electoral votes, the Keystone State has long tempted Republicans hoping to make inroads with Rust Belt voters. In 2012, Mitt Romney's campaign made a late push in the state, and this year Donald Trump has boasted that he will win Pennsylvania.

Prior to 1988, Republicans did have success in Pennsylvania, winning the state in 1984 and 1980 with the help of Reagan Democrats. In 1976, the Democrats prevailed with Jimmy Carter getting the state's votes.

It is an uphill climb for Republicans, but early signs show Trump may have something of a chance at swinging a state that has eluded the Grand Old Party for 28 years.

However, Democrats start with a significant registration edge in the state. The party has nearly 1 million more registered members than Republicans, according to state voter data.

Trump starts with a significant disadvantage, but he has sought to capitalize on his appeal among blue-collar voters. Last month, he blasted free trade agreements and decried the loss of manufacturing jobs in a major speech near Pittsburgh. The National Rifle Association is also targeting the state on behalf of Trump with an early advertising push.

He may find significant traction in the heartland of a state that political strategist James Carville memorably characterized as "Pennsylvania is Philadelphia and Pittsburgh with Alabama in between."

There are signs Trump has a chance, though the odds remain in Clinton's favor. Writing for website FiveThirtyEight, David Wasserman found that Pennsylvania has been migrating toward Republicans as opposed to the way the rest of the country is trending.

"[Pennsylvania has] gotten about 0.4 percentage points more Republican every four years," Wasserman wrote. "Western Pennsylvania is driving the state's rightward drift — its voting patterns now resemble greater Appalachia's more than those of the Philadelphia suburbs."

Indeed, Democrats are not taking the state for granted: A super PAC supporting Clinton will spend $10.5 million in the state through election day. Clinton herself will embark on a bus tour after the convention, traveling through western Pennsylvania with running mate Sen. Tim Kaine.

Pennsylvania may have a blue voting record when it comes to the presidential level, but it has a congressional delegation dominated by the Republican Party, and a state capitol with both chambers controlled by Republicans.

"I've warned Democrats: Donald Trump is giving a message and it's resonating with white, blue-collar workers who work in factories, who work on construction crews," former Pennsylvania Gov. Ed Rendell said at a Politico event Tuesday. "This state is in play."

Pennsylvania is among other top swing states this cycle, including Florida, Ohio and Colorado.